Topological Photonic Lattice

Topological photonics builds photonic band structures whose light-guiding channels are protected by a topological invariant rather than by careful fabrication. This simulation renders a honeycomb lattice of coupled optical resonators and launches two light pulses through it: one confined to the topological edge state running along the lattice boundary, and one travelling freely through the bulk. A defect site sits in the path of each. The bulk pulse backscatters off it, losing energy to Rayleigh-like scattering, while the edge pulse — protected by bulk–boundary correspondence — continues forward with almost no reflection, because the trivial phase on the other side of the boundary leaves it nowhere to scatter into. Flip the topological phase to watch that protection vanish: with the Chern number set to zero, the same "edge" channel backscatters exactly like the bulk.